Spin-blast apparatus

ABSTRACT

In a spin-blast apparatus for cleaning the interior of a pipe, in which abrasive is fed to a rotary blast nozzle caused to travel interiorly along the pipe, and in which the nozzle is mounted on a support conduit journalled for rotation within a non-rotating housing by bearings, the intake end of the support conduit bears against a sealing gasket which is supported by clamping means in such a way as to prevent excessive leakage of abrasive past the gasket. The clamping means is spaced from the end of the housing so as to define therewith a space which is open to atmosphere; thus, any abrasive which leaks past the gasket will fall from the apparatus and will not be forced under air pressure into the bearings.

United States Patent [191 Jarvis [4 1 Sept. 2, 1975 SPIN-BLAST APPARATUS [76] Inventor: Harold F. Jarvis, R.R. No. 1,

Moffat, Ontario, Canada [22] Filed: Dec. 3, 1974" [21] Appl. No.: 529,069

Primary Examiner-Donald G. Kelly ABSTRACT In a spin-blast apparatus for cleaning the interior of a pipe, in which abrasive is fed to a rotary blast nozzle caused to travel interiorly along the pipe, and in which the nozzle is mounted on a support conduit journalled for rotation within a non-rotating housing by bearings, the intake end of the support conduit bears against a sealing gasket which is supported by clamping means in such a way as to prevent excessive leakage of abrasive past the gasket. The clamping means is spaced from the end of the housing so as to define therewith a space which is open to atmosphere; thus, any abrasive which leaks past the gasket will fall from the apparatus and will not be forced under air pressure into the bearings.

9 Claims, 5 Drawing Figures PAT TEBSEP 2 SPIN-BLAST APPARATUS BACKGROUND OF THE INVENTION usually a plurality of nozzles of an assembly, so as to sweep the interior surface of the pipe and clean it by abrasive action.

As a swivel connection between thenozzle head and the supply conduit must be provided, it is usual to mount the nozzle head on a tubular adaptor, or support conduit, which is journalled for rotation within a nonrotating housing by which the supply conduit is supported in registration with the support conduit. As the bearings of such an arrangement are extremely vulnerable to the abrasive action of the sand, the protection of the bearings from such action presents a serious problem. In the past, the only approach to this problem has been based on the obvious expedient of enclosing the bearings, as far as possible, to prevent ingress of sand. However, this approach has not yet yielded a satisfactory solution.

The present invention is based on a completely different approach, namely to ensure that any sand which does leak from the high pressure zone of the apparatus will have been isolated from the high pressure blast.

SUMMARY OF THE INVENTION According to the invention, the intake end of the nozzle support conduit bears against an inner peripheral portion of an annular sealing gasket which is supported by clamping means in such a way as to minimize leakage of abrasive from the high pressure zone. The clamping means is spaced from the end of the housing by spacers, so as to provide a space at atmospheric pressure into which any leakage of abrasive must flow. Thus, any abrasive which leaks from the high pressure zone will have been isolated from the blast and will fall from the apparatus without being forced into the bearmgs.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1' is a diagrammatic illustration of an apparatus in use in a sandblasting plant;

FIG. 2 is a side view of a carriage forming part of the apparatus;

FIG. 3 is a section on line 33 in FIG. 2;

FIG. 4 is an enlarged half-sectional elevation of a swivel assembly forming a part of the apparatus; and

FIG. 5 is a section on line 5-5 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. I the pipe to be cleaned is shown at 10, the pipe being supported horizontally. A carriage 11 which is adapted to travel interiorly along the pipe carries a rotating nozzle head 12 to which a continuous blast of abrasive air/sand mixture is supplied under pressure via a blast supply conduit 13. The nozzle head 12 is coupled to the blast supply conduit 13 by a swivel assembly, which will be described subsequently. The carriage 11 is shown parked on a trolley 14, the axis of the nozzle head being aligned with the axis of the pipe 10, and the rear end of the supply conduit I3 is supported by a trolley 15. The blast is derived by recirculating air under pressure from a reclaiming and recirculating unit 16 via a pipe 17. Electric power lines for supplying power to the motive elements of the apparatus are indicated schematically at 18. As the trolley is advanced, the carriage 11 is caused to travel along the pipe, a continuous blast of abrasive being projected from the nozzles of the rotating nozzle head 12 so as to sweep and clean the interior surface of the pipe 10.

As shown in FIG. 2, the nozzle head 12 has a pair of nozzles 19 which are inclined. to the horizontal rotary axis of the nozzle head. The head is rotated by an electric motor 20 mounted on the carriage 11, the drive being transmitted from the motor via a drive shaft 21 and a chain and sprocket drive 22. The abrasive blast is fed from the supply conduit 13 to the nozzles via a swivel assembly 23, which will now be described with reference to FIGS. 4 and 5 in particular.

The swivel assembly 23 comprises a cylindrical housing 24 in which a tubular nozzle support conduit 25 is journalled for rotation about a horizontal axis. The conduit 25 has a discharge end which projects from one end of the housing 24, the dischargeend being externally threaded as shown at 26, this end being adapted for connection to the nozzle head 12 by threaded engagement therewith. The intake end of the conduit 25 projects from the other end of the housing 24, which is provided with an annular clamping flange 27. The conduit 25 is located by bearing means in the housing 24 so as to be coaxial therewith, the bearing means being constituted by two axially spaced ball bearing assem blies 28, 29, the races of which are axially located by stops machined into the housing and the support conduit, respectively. The bearing assemblies are protected from the ingress of abrasive and dust by means of annular partitions 30, 31 located between the cylindrical housing 24 and the support conduit 25 adjacent to the ends of the housing. Each of the annular partitions has an outer flange 32, 33 which is secured to the internal surface of the cylindrical bore of the housing, and an inner flange 34, 35 formed with a circumferential ridge which is held in sliding contact with the support conduit by means of a respective circlip 36, 37.

The supply conduit 13 is coupled to the swivel assembly by means ofa flanged adaptor 38, the flanged adaptor having an internally threaded tubular portion 39 which engages the externally threaded end of the supply conduit. The supply conduit 13 has a lining of hard rubber 40. An annular sealing; gasket of leather 4] is clamped between the flanged end of the adaptor 38 and an annular clamping plate 42, the gasket 41 having an inner peripheral portion 41A which extend radially inwards beyond the inner periphery of the clamping plate 42 so as to define a central circular opening of substantially the same diameter as the internal diameter of the lining 40 and the internal diameter of the support conduit 25. The support conduit 25 is so positioned that its intake end bears against one side of the peripheral gasket portion 41A; an annular hard washer which defines the discharge end of the supply conduit 13, bears against the opposite side of said peripheral gasket portion. The washer 43 provides a circular opening of the same diameter as the opening provided by the gasket M.

The flanged adaptor 38 and clamping plate 42, between which the gasket 41 is held, are clamped to the flanged end of the cylindrical housing 24 by clamping bolts 44, the clamping plate 42 being spaced axially from the end of the housing by bushings or spacers 45. In this way the clamping plate 42 defines with the end of the housing a space which is open to atmosphere, and into which any sand that might leak past the gasket 41 must pass. Thus, any sand which leaks past the gasket, being in a low pressure region, will fall from, or be centrifugally thrown from, the assembly rather than penetrate into the bearing assemblies. In order to permit compensation for wear on the peripheral portion 4lA of the gasket 4], shims 48 are mounted on the bolts 44 between the spacers 45 and the flange 27. As the peripheral portion of the gasket becomes worn, the shims may be removed as necessary so as to maintain a good seal between the gasket and the end of the conduit 25.

It is important to note that the gasket 4] is backed by air at high pressure in a space 46, the opposite side of the gasket being exposed to atmospheric pressure. Thus there will be a pressure differential acting on the opposite sides of the gasket so as to maintain the peripheral portion of the gasket in sealing contact with the annular end face of the nozzle support conduit 25.

What I claim as my invention is:

1. In an apparatus for abrading the interior surface of a pipe by blasting abrasive from a rotating nozzle which is caused to, travel interiorly along the pipe, a swivel assembly for coupling the rotating nozzle to a blast supply conduit, comprising:

a cylindrical housing,

a tubular nozzle support conduit journalled for rotation within the housing,

the support conduit having a discharge end projecting from one end of the housing for connection to the nozzle and an intake end projecting from the other end of the housing,

a flanged adaptor having a tubular portion for connection to the supply conduit.

an annular clamping plate,

means clamping the adaptor and the clamping plate to said other end of the housing coaxially therewith, an annular sealing gasket clamped between the flanged adaptor and the clamping plate, the gasket having a peripheral portion extending radially inwards beyond the inner periphery of the clamping plate,

the intake end of the support conduit bearing against said peripheral .portion of the gasket, I

the clamping plate being spaced from said other end of the cylindrical housing by spacers to define therewith a space which is open to atmosphere.

2. A swivel assembly according to claim 1, wherein the inner peripheral edge of the gasket is substantially aligned with the interior surface of the support conduit.

3. A swivel assembly according to claim 1, wherein the support conduit is journalled within the cylindrical housing by ball bearing assemblies, the ball hearing assemblies being isolated from said space by annular partitions located between the housing and the support conduit adjacent to the ends of the housing.

4. Apparatus for abrading the interior surface of a pipe, comprising:

a carriage adapted to travel interiorly along the pipe,

a cylindrical housing mounted on the carriage, the cylindrical housing having an axis aligned with the axis of the pipe along which the carriage is adapted to travel,

a tubular nozzle support conduit journalled for rotation within the housing by bearing means, said bearing means locating the support conduit coaxially with the housing,

the support conduit having a discharge end projecting from one end of the housing and an intake end projecting from the other end of the housing,

a rotary nozzle assembly coupled to said discharge end,

a blast supply conduit for supplying an air/abrasive mixture under pressure to the intake of the support conduit,

a flanged adaptor having a tubular portion to which the supply conduit is connected,

an annular clamping plate,

means clamping the adaptor and the clamping plate to said other end of the housing coaxially therewith,

an annular sealing gasket clamped between the flanged adaptor and the clamping plate, the gasket having a peripheral portion extending radially inwards beyond the inner periphery of the clamping plate,

the intake end of the support conduit and the dis charge end of the supply conduit bearing against opposite sides of said peripheral portion, and

spacers interposed between the clamping plate and said other end of the cylindrical housing whereby to define therebetween a space which is open to atmosphere.

5. Apparatus according to claim 4, wherein the discharge end of the supply conduit is constituted by an annular hard washer.

6. Apparatus according to claim 5, wherein the supply conduit and the support conduit are of the same internal diameter, said gasket and said hard washer each providing a circular opening of the same diameter as said internal diameter.

7. Apparatus according to claim 4, said bearing means being enclosed between annular partitions located between the housing and the support conduit adjacent to the ends of the housing.

8. Apparatus according to claim 7, said bearing,

means being constituted by a pair of axially spaced ball bearing assemblies. I 9. Apparatus according to claim 4, wherein the nozzle assembly is driven by an electric motor mounted on the carriage. 

1. In an apparatus for abrading the interior surface of a pipe by blasting abrasive from a rotating nozzle which is caused to travel interiorly along the pipe, a swivel assembly for coupling the rotating nozzle to a blast supply conduit, comprising: a cylindrical housing, a tubular nozzle support conduit journalled for rotation within the housing, the support conduit having a discharge end projecting from one end of the housing for connection to the nozzle and an intake end projecting from the other end of the housing, a flanged adaptor having a tubular portion for connection to the supply conduit, an annular clamping plate, means clamping the adaptor and the clamping plate to said other end of the housing coaxially therewith, an annular sealing gasket clamped between the flanged adaptor and the clamping plate, the gasket having a peripheral portion extending radially inwards beyond the inner periphery of the clamping plate, the intake end of the support conduit bearing against said peripheral portion of the gasket, the clamping plate being spaced from said other end of the cylindrical housing by spacers to define therewith a space which is open to atmosphere.
 2. A swivel assembly according to claim 1, wherein the inner peripheral edge of the gasket is substantially aligned with the interior surface of the support conduit.
 3. A swivel assembly according to claim 1, wherein the support conduit is journalled within the cylindrical housing by ball bearing assemblies, the ball bearing assemblies being isolated from said space by annular partitions located between the housing and the support conduit adjacent to the ends of the housing.
 4. Apparatus for abrading the interior surface of a pipe, comprising: a carriage adapted to travel interiorly along the pipe, a cylindrical housing mounted on the carriage, the cylindrical housing having an axis aligned with the axis of the pipe along which the carriage is adapted to travel, a tubular nozzle support conduit journalled for rotation within the housing by bearing means, said bearing means locating the support conduit coaxially with the housing, the support conduit having a discharge end projecting from one end of the housing and an intake end projecting from the other end of the housing, a rotary nozzle assembly coupled to said discharge end, a blast supply conduit for supplying an air/abrasive mixture under pressure to the intake of the support conduit, a flanged adaptor having a tubular portion to which the supply conduit is connected, an annular clamping plate, means clamping the adaptor and the clamping plate to said other end of the housing coaxially therewith, an annular sealing gasket clamped between the flanged adaptor and the clamping plate, the gasket having a peripheral portion extending radially inwards beyond the inner periphery of the clamping plate, the intake end of the support conduit and the discharge end of the supply conduit bearing against opposite sides of said peripheral portion, and spacers interposed between the clamping plate and said other end of the cylindrical housing whereby to define therebetween a space which is open to atmosphere.
 5. Apparatus according to claim 4, wherein the discharge end of the supply conduit is constituted by an annular hard washer.
 6. Apparatus according to claim 5, wherein the supply conduit and the support conduit are of the same internal diameter, said gasket and said hard washer each providing a circular opening of the same diameter as said internal diameter.
 7. Apparatus according to claim 4, said bearing means being enclosed between annular partitions located between the housing and the support conduit adjacent to the ends of the housing.
 8. Apparatus according to claim 7, said bearing means being constituted by a pair of axially spaced ball bearing assemblies.
 9. Apparatus according to claim 4, wherein the nozzle assembly is driven by an electric motor mounted on the carriage. 